What causes aggression?
• Various theories
• One of the most common debates involves
internal vs. external factors
• i.e., nature vs. nurture
• Internal factors: We are naturally aggressive;
we are born with aggressive tendencies
• External factors: Our environment and
experiences lead us to become aggressive

Evolutionary theories of
aggression
• Also called ‘instinct’ theories:
– suggest aggression is a part of human
nature
– Aggression is an instinct, perhaps an
inevitable part of human behavior
– We are ‘programmed’ for violence by our
biological nature

• Humans (and other species) physically fought
over potential mates
– the best fighters were able to win the mate and have
their genes passed on

Modern evolutionary
approaches
• Behaviours that help individuals procreate will
become increasingly prevalent in the species’
population
• Used to explain ‘young male syndrome’:
– young males are more likely to be involved in
violence and risk-taking than older males or females
of any age
– Why? Competition for reproductive success

• Males fight with each other over resources in
order to attract a female and have their genes
passed on

Modern evolutionary
approaches: Research
• Mesquida & Wiener, 1996
• Across 88 countries from the years 1980 to 1993, the
more young males in a population the more severe the
group violence
• Why? There are fewer resources to go around, thus
hindering the young males’ ability to mate
• Thus, the young males are better served to band
together and fight for resources – collective aggression
• Manifested in uprisings, revolutions, even war
• These results are correlational, not causational
– alternative explanations include poverty and political instability

Critiques of modern
evolutionary approaches
• Even evolutionary theorists point out that
instinctive tendencies likely interact with other
factors (environmental, internal) to produce
aggression
• Most social psychologists have rejected early
instinct theories because:
– The causes of human aggression are multi-faceted
(not just instincts)
– The fighting described by evolutionary psychologists
is fairly tame, whereas typical human aggression is
much more severe (e.g., leading to death)
– The innate tendency to kill makes less sense than
the innate tendency to do temporary harm

Critiques of modern
evolutionary approaches
• There are many more forms of human
aggression than physical: e.g., passiveaggressive, spreading rumors,
destroying property, and direct verbal
aggression
• Wide cultural variations in aggression:
innate tendencies would predict crosscultural consistency
• No support for catharsis hypothesis

Other biological theories
• Genetic factors may be important
– twin/adoption studies support the role of genetics in
aggressive behaviour

Type A Personality:
Research
• Research evidence: Type A = more aggressive (e.g.,
hostile aggression, spousal/child abuse)
• When provoked, Type A’s more likely to retaliate with a
(fake) electric shock
– Especially true for Type A's w/ high testosterone

• Type A not related to instrumental aggression
– aggression aimed at attaining goals such as resources or
praise

• Type A also believed to be related to coronary heart
disease

Current state of Type A
personality research
• Recently, Type A personality has been
replaced by trait hostility
• Trait hostility explains the relationship
between Type A personality and many
outcomes (e.g., coronary heart disease)
• Other aspects of Type A (e.g., always in
a hurry, competitiveness) do not predict
these outcomes

The Dark Triad of
Personality
• Aversive traits found outside of prison samples
• Narcissism: grandiosity, self-enhancement,
self-centered
• Machiavellianism: manipulative, cynical
• Psychopathy: less extreme than the version
found in prison samples
• Although all three predict antisocial behaviour,
psychopathy produces the strongest and most
consistent links

Benefit of personality
theories
• Personality traits tend to be stable across
time and situations
• Thus, personality may allow for
generalized predictions
• E.g., people who are aggressive in the
workplace will likely also be aggressive
at home (spousal abuse), etc.
• Would child bullies grow up to become
aggressive adults?

Aggression: The role of
arousal
• We have already seen that many internal
and external factors have been linked to
aggression
• Other theories involve arousal:
– Any physiological excitement
– e.g., rapid heartbeat, ‘adrenaline rush’,
‘butterflies in the stomach’

• We may then be more likely to react to
subsequent situations with aggression
– e.g., if you are highly aroused, a situation that may
normally only make you mildly annoyed would
instead cause you to be extremely angry

Excitation transfer theory
• Aggression is most likely to occur when:
• persons are unaware of the presence of
residual arousal (research has demonstrated
that small levels of arousal tend to go
unnoticed)
• you notice the arousal but mistakenly
attribute it to the new situation

• The nature of the post-arousal situation
is highly important:
• Recall we may also interpret arousal as
sexual attraction (Capilano bridge study)

Sexual arousal and aggression
â&#x20AC;˘ Relationship between sexual arousal and
aggression is curvilinear :
High

Aggression
Levels

Low
None

Mild

Sexual Arousal

High

Sexual arousal and aggression:
Crimes of passion?
• Does intense sexual arousal play a role
in crimes of passion?
– No direct evidence

• However, sexual jealousy, which evokes
powerful feelings of anger and
aggression, does appear to be related to
crimes of passion
• Possible that sexual jealousy may
combine with high arousal to predict
crimes of passion (but again, no direct
evidence)

• e.g., what roles do the environment and our
social experiences play in predicting
aggressive behaviour?

Drive theories: The role of
frustration
• Humans have an internal motive or drive to harm
others, which normally lays dormant
• When exposed to certain external conditions, this
drive is aroused and the result is aggression
• External conditions may include loss of face or
frustration
External
Aggressive
Aggressive
condition
Drive
Behaviour

• Summarized by the frustration-aggression
hypothesis:
– (1) frustration always leads to some form of aggression,
and
– (2) aggression always stems from frustration (i.e., there

Frustration-aggression
hypothesis: Research
• However, researchers subsequently determined that the
frustration-aggression hypothesis is only partially correct
• Frustration leads to aggression because frustration is an
aversive, unpleasant feeling
• However, frustration is not the only aversive emotion:
– others include anger, nervousness, impatience, irritability, etc.

• Other research evidence: frustration is more likely to
produce aggression when it is either unexpected or
illegitimate
• Why? Likely because these types of frustration are more
aversive than when it is expected or legitimate

Social learning theory
• Bandura (1973)
• Aggression is learned either through direct experience
or by observing others
• Evidenced in how different cultures express aggression
(e.g., martial arts vs. firearms)
• Through these channels, individuals also learn:
– (1) appropriate targets for aggression
– (2) what actions by others require or justify aggression, and
– (3) the situations or contexts in which aggression is
appropriate

• This model has been particularly helpful in describing
spousal abuse
– i.e., some husbands abuse their wives because they have
seen their fathers abuse their mothers

Media violence

Media violence
• Most of us observe much more violence
through media than we are ever to
encounter first-hand in real life
• This point is true even if you remove real
violence we observe through the media
(e.g., on the news, etc.)
• What affect (if any) does this exposure
have on our own aggressive behaviour?

Media Violence: Research

• Exposure to media violence may indeed increase levels of
aggression
• E.g., short-term laboratory experiments:
– individuals exposed to aggressive media, then given an opportunity to
aggress against another individual (usually a confederate)
– Compared to individuals who are exposed to non-violent media, these
individuals subsequently aggress more (however, the differences are
often quite small)

• Similar results for longitudinal studies, and the results are
consistent across countries
• It is important to note that the majority of these studies are
correlational in nature
– i.e., does media influence aggression, or do existing aggressive
tendencies influence media preferences?

Media violence: Other
evidence
• Individuals may learn new ways of aggressing
from watching TV and movies; ways they
would not have imagined before (e.g., "copycat
crimes")
• The Dallas Morning News , July 1, 1999:
– “7 year old kid kills his 3 year old brother with a
wrestling move.”

Media violence: The role of
individual differences
• Reciprocal determinism theory: (Bandura,
1977)
• Certain individuals are attracted to certain
types of media (e.g., violent)
• These individuals are also affected by this
media differently than people who are not
attracted to it

Research evidence
• Antisocial personalities (e.g., psychopathy) are
more attracted to violent media of various kinds
(e.g., music, movies, video games sports)
• Engaging in violent sports predicts aggressive
behaviour only for psychopaths
• No aggression among non-psychopaths who
engage in violent sports, or psychopaths who
do not engage in violent sports

Cultural differences in
media effects
â&#x20AC;˘ The effects of media violence differ as a
function of personality (e.g.,
psychopathy), but also consider culture:
â&#x20AC;˘ Canadians and Americans are exposed
to virtually the same amount of media
violence, yet there is much more violence
in the U.S.

Explaining the media violenceaggression link
• Desensitization:
– With repeated exposure over time, individuals
become hardened to the suffering of others;
emotional reactions become lower

• Priming of hostile thoughts:
– violent media causes violence to become 'hardwired' as a reflex reaction to provocations, for
example

Workplace aggression

• Presumably another example of
social forces causing aggression
(e.g., being fired)
• Acts of workplace aggression tend
to steal the headlines, but:
• 1) most workplace aggression is
conducted by individuals from
outside the workplace (e.g., thieves)
• 2) it is very rare to be a victim of
workplace violence

The role of cognitions in
aggression
• Aggression is often the result of
provocation (a social factor)
– E.g., Chermack et al. (1997): as the level of
provocation increased, participants gave
stronger retaliation (electric shocks)
– In other words, individuals want to 'pay back'
any aggression they are exposed to with an
equal level of aggression, or in some cases,
even more aggression

• However, other peoples’ intentions are
not always clear:
– there is a subjective element to provocation

Cognition and provocation
• Hostile attribution bias (HAB)
• Tendency to perceive aggression in others'
intentions even when there is none present
(i.e., ambiguous or neutral situations)
• For example, accidentally bumping into
someone in a crowded area, or even simple
eye contact
– An HAB individual will be more likely to perceive
these acts as hostile

– More likely to respond to threats with anger and
violence
– More accepting of violence (and even murder) as
a problem-solving strategy
– More accepting of violent people/murderers
– Also show increases in testosterone when
provoked (recall biological theories of aggression)

An integrative theory:
General Affective Aggression Model
• Anderson, 1996 (GAAM)
• Integrates the influence of internal and
external forces in predicting aggression
• Aggression is triggered/elicited by various
input variables – either aspects of the
situation or pre-existing individual differences
• Once triggered, there are various routes to
aggression

• Individual differences include:
– Personality (irritability, hostility, Dark Triad, disagreeableness)
– Attitudes/beliefs about violence (i.e., that it is
acceptable/appropriate)
– Values about violence (i.e., that it is a ‘good’ thing – that there
are benefits)
– ‘Aggression skills’ (knowing how to fight, use weapons, etc.)

Sex differences in
aggression
• Widespread belief that males are more
aggressive than females
• Some research support for this belief:
– Males report higher rates of aggressive behaviors
than females

• But: males are also more likely to be the victims
of aggression
– Likely due to males aggressing against other males

• This difference persists throughout the lifespan
– e.g., in people as high in age as 70 or 80

• Overall, gender differences tend to be minor,
though there are some complexities:
– Depends on situation and type of aggression

Sex and situation
interactions
• Sex differences become more apparent
when examining provocations
• Compared to females, males much more
likely to aggress in situations when they
are not provoked
• There is virtually no gender difference
when provocation is involved

• Objectivity:
– What are the ‘units’ of aggression?
– Number of punches? Volume of voice?

Aggression: Research
methods
• There are various methods, each with
advantages and disadvantages
• Experimental methods:
– e.g., participant is allowed to aggress
against a confederate after false negative
feedback
– Participant administers electroshock or noise
blast

• Pros: can be measured objectively
• Cons: not very realistic; ethics

Aggression: Research
methods
• Pencil-and-paper methods:
– Self-reports: Participants write down the
number of times they have committed
various aggressive acts
– Peer-reports: Someone who knows the
research participant reports their aggression

Preventing and controlling
aggression
• Is punishment an effective deterrent?
• Yes – under certain conditions
• i.e., punishment must be:
– prompt – must follow aggressive actions as quickly
as possible
– certain – the probability that it will follow aggression
must be very high
– strong – strong enough to be highly unpleasant to
potential recipients
– appropriate – perceived by recipients as justified or
deserved

Learning to reduce
aggression
• Interventions based on social learning theory
• Exposure to non-aggressive models – e.g.,
showing examples of:
– people who do not retaliate when provoked
– people who are forgiving
– non-violent role models (Gandhi)

• Social skills training:
– i.e., teaching people to make/refuse requests
without making others angry

Reducing aggression through
catharsis
• An early idea (1939)
• Venting anger and hostility in a relatively
safe way will reduce later aggression
• Two important benefits:
– 1) helps to reduce emotional tension
– 2) since they help to eliminate anger,
venting reduces the likelihood of more
dangerous forms of aggression

Catharsis research: Mixed
results

• Participation in various activities that are not
harmful to others (e.g., working out) can reduce
emotional arousal stemming from frustration or
provocation
• However, these effects are temporary:
– arousal reappears quickly, simply by remembering
the incident that made you angry in the first place

• Using overt physical aggression also does not
work, and may actually increase subsequent
aggression
– Examples: watching media violence, hitting a
punching bag, or yelling at someone
– Recall effects of violent sports and pornography for
psychopaths (though direction of causality remains
an issue)

Cognitive interventions
â&#x20AC;˘ Why are interventions important?
Without intervention, one consequence is
displaced aggression:
â&#x20AC;&#x201C; the tendency to lash out against
unrelated/innocent others

â&#x20AC;˘ Apologizing to someone who is
aggressive (expressing regret and asking
for forgiveness) is effective in reducing
their aggression

Cognitive interventions
• The idea behind cognitive interventions is
that when we are very angry, our ability
to think clearly is reduced
– e.g., ability to consider the consequences of
our actions

• When we are angry we 'lose (cognitive)
control' – these activities help us to
recover control

Exceptions: Treatment of
psychopaths
• Correctional programs tend to be aimed at
developing empathy, conscience, interpersonal
skills
• Criminal psychopaths typically do not show
behavioural improvements from treatment
• Why? Psychopaths do not experience personal
distress, see nothing wrong with their behaviour,
and do not seek treatment unless forced
• In some cases, psychopaths become more
adept at criminal behaviour and manipulation
following treatment

Summary
• Overall, gender differences in aggression tend
to be minor, though there are some
complexities
• Most cultural differences in aggression occur in
subcultures within larger cultures
• There are several methods of studying
aggression, each with advantages and
disadvantages
• Various strategies for deterring and reducing
aggression exist, each with varying degrees of
success